Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:4.1.1.17 (ornithine decarboxylase)
6,351 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Ornithine decarboxylase has been induced in log phase hepatoma cells grown in suspension culture. Induction with N6, O2'-dibutyryl cyclic adenosine 3':5'-monophosphate produced a 4-fold increase in enzyme activity by 3 hours which was followed by a return to base levels by 6 hours. Induction with dexamethasone, a potent synthetic glucocorticoid, exhibited a slow steady rate of increase in enzyme activity, reaching a plateau level of approximately 5- to 6-fold stimulation by about 12 hours. Induced cell and regenerating rat liver ornithine decarboxylase were shown to be indistinguishable by titration with antibody monospecific to the latter and by heat stability. L-[14C]Leucine incorporation into immunoprecipitable enzyme protein after induction in vitro or partial hepatectomy showed an increase which, when coupled with the increase in enzymatic activity, indicated de novo synthesis of enzyme protein. Physiological concentrations of the naturally occurring polyamines, spermidine and spermine, abolish cyclic AMP induction whereas they have no effect on dexamethasone induction. Both inductions were abolished by cycloheximide; in contrast, inhibition by actinomycin D was complete for dexamethasone induction and only partial with respect to cyclic AMP induction. The different time pattern of induction seen with cyclic AMP and dexamethasone, the partial inhibition of the cyclic AMP induction seen with actinomycin D, as well as the absence of inhibition of the dexamethasone induction by polyamines, indicate that these inducers might affect different aspects of the control of the same enzyme.
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PMID:Stimulation of ornithine decarboxylase synthesis and its control by polyamines in regenerating rat liver and cultured rat hepatoma cells. 18 26

Stimuli known to induce tyrosine aminotransferase in H35 cells were tested relative to their ability to induce ornithine decarboxylase, the initial enzyme in the polyamine biosynthetic pathway. Dibutyryl cyclic AMP (0.5 mM), parachlorophenylthio-cyclic AMP (0.1 mM) and dexamethasone (1 muM) stimulated the activity of ornithine decarboxylase 7- to 8-fold by 5 hr of induction. There was a delay of 1 hr before any increase in enzyme activity was detectable. Insulin administered alone failed to significantly change ornithine decarboxylase activity. The ability of dibutyryl cyclic AMP to elevate ornithine decarboxylase activity was found to be concentration-dependent, and a dose-response relationship very similar to that for the induction of tyrosine aminotransferase by dibutyryl cyclic AMP was observed in these cells. The ability of various 8-substituted cyclic AMP analogues to increase the activity of ornithine decarboxylase was correlated with their ability to activate purified protein kinase.
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PMID:Induction of ornithine decarboxylase in Reuber H35 rat hepatoma cells. 18 23

Single pharmacological doses of parathyroid hormone, calcitonin, vasopressin, d-aldosterone, or L-triiodothyronine produced a significant increase in the ornithine decarboxylase activity of rat kidney. The activity of kidney ornithine decarboxylase was also enhanced by other hormones, such as pentagastrin and serotonin, which, although they are not known to modify kidney physiology, are secreted by cells having close relationships to the calcitonin-secreting parafollicular cells. The induction of the enzyme was observed in hypophysectomized rats, with or without some other hormone-secreting glands remaining. However, the magnitude of the stimulation elicited by the hormones was somewhat diminished in animals still having the endocrine gland whose hormone was being tested. The maximal stimulation of kidney ornithine decarboxylase activity by parathyroid hormone, calcitonin, vasopressin, L-triiodothyronine, pentagastrin, and serotonin occurred at 4 h after the hormone injection. The enhancement in ornithine decarboxylase activity produced by d-aldosterone was maximal at 3 h after the injection of the hormone. The content of ornithine in the kidney was found to be virtually unchanged whatever the type of hormone treatment. No statistically significant increases in renal ornithine decarboxylase activity of hypophysectomized animals were observed after injection of melatonin or of vitamin D3. Since the stimulating hormones possess clearly different mechanisms of action, the role of cyclic AMP as a general mediator of ornithine decarboxylase induction is questioned.
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PMID:In vivo hormonal induction of ornithine decarboxylase in rat kidney. 18 46

The activity of ornithine decarboxylase [EC 4.1.1.17] (ODC) in mouse L cells in the confluent state was induced within 4 hr by cyclic AMP (cAMP) or by insulin. During growth of L cells the concentration of cAMP increased first, then induction of ODC occurred and finally the cell number increased: the levels of cAMP and ODC increased only transitorily and returned to the basal levels when the cells become confluent. In growing cultures, however, the presence of cAMP reduced induction of ODC and cell growth. These results suggest that cAMP is involved in induction of ODC and that its concentration may be important for enzyme induction as well as for cell growth. Actinomycin D with or without these inducers stimulated induction of ODC in L cells, whereas cycloheximide inhibited it, suggesting that these hormones affect the translational level of ODC synthesis. The effect of actinomycin D on induction of ODC was much greater in non-growing cells than in growing cells. It was also found that the half life of ODC was 81 min in non-growing cells and 112 min in growing cells. This suggests that turnover of the enzyme is more rapid in the non-growing than in the growing state and that there may be an RNA fraction which controls its turnover and which also has a very short half life.
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PMID:Induction of ornithine decarboxylase in cultured mouse L cells. I. Effects of cellular growth, hormones, and actinomycin D. 18 1

Infection of primary cultures of mouse kidney cells with polyoma virus causes a biphasic increase in the activities of L-ornithine decarboxylase (ODC; L-ornithine carboxy-lyase; EC 4.1.1.17) and S-adenosyl-L-methionine decarboxylase (SAMD; S-adenoxyl-L-methionine carboxy-lyase; EC 4.1.50), as well as in the level of the polyamines putrescine, spermidine, and spermine. An early peak occurs during the period when early viral mRNA is synthesized and prior to the onset of virus-induced synthesis of host cell DNA. A late peak coincides in time with the maximum rate of virus-induced synthesis of cellular DNA. A similar biphasic stimulation of polyamine synthesis is induced even when DNA synthesis is prevented by 5-fluorodeoxyuridine. Actinomycin D (AMD) in a dose that inhibits rRNA synthesis causes no inhibition of ODC or SAMD. In a dose that inhibits mRNA synthesis as well, short-term AMD treatment causes "superinduction" of ODC but inhibition of SAMD. Prolonged treatment with the high dose of AMD inhibits ODC as well, indicating that late ODC activity may be dependent on mRNA synthesized during early infection. Cycloheximide effectively obliterates the ODC and SAMD activities during the entire infectious cycle. Uncoupling from DNA and rRNA synthesis suggests that polyamine synthesis is regulated independently of these events. The experiments with AMD and cycloheximide suggest that the formation of ODC is subject to post-transcriptional control, whereas that of SAMD is regulated primarily at the transcriptional level.
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PMID:Biphasic stimulation of polyamine biosynthesis in primary mouse kidney cells by infection with polyoma virus:uncoupling from DNA and rRNA synthesis. 18 74

Studies were carried out to determine whether the actions of prolactin on the metabolism of the mammary gland may involve polyamines. In mouse mammary gland explants that were preincubated for 2 days with insulin plus hydrocortisone, the rate of [3H]leucine incorporation into casein was enhanced in a prolactin-like manner during a further incubation with spermidine plus cyclic GMP or phospholipase A. Putrescine (0.5 mM) plus PGF2alpha, cyclic GMP or arachidonic acid also enhanced the rate of casein synthesis: but PGF2alpha plus 0.5 mM arginine, ornithine or spermine had no effect. Methyl GAG, an inhibitor of the enzyme S-adenosyl-L-methionine decarboxylase (which is required for the conversion of putrescine to spermidine), abolished the putrescine plus PGF2alpha stimulation of casein synthesis. Since this drug did not affect the action of spermidine plus PGF2alpha on casein synthesis, the specific action of spermidine on casein synthesis is suggested. Neither arginine, ornithine nor the polyamines, by themselves, affected the rate of [3H]uridine incorporation into RNA or the rate of [3H]leucine incorporation into casein. Spermidine levels were elevated within 4 h after adding prolactin to explants which were preincubated for 2 days with insulin plus hydrocortisone; this effect was apparent during incubation periods of up to 48 h with prolactin. Arginase and ornithine decarboxylase activities were also elevated in response to prolactin. Arginase activity was only elevated, however, during long incubation periods with prolactin, i.e., during incubation periods of longer than 2 days. In contrast, ornithine decarboxylase activity was elevated by prolactin within a 30 min incubation period; this effect was maximal after 2 h and persisted during exposure periods of up to 24 h.
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PMID:Regulation of casein synthesis by polyamines in mammary gland explants of mice. 18 30

Induction of ornithine decarboxylase [EC 4.1.1.17] (ODC) in mouse L cells by components of the culture medium was investigated. It was found that further addition of amino acid mixture, but not of calf serum, to confluent cells of 5 day culture induced ODC and that this induction was accelerated by actinactinomycin D. In salt solution, addition of either amino acids or serum alone did not cause full induction, but addition of both together did. This induction, in contrast, was inhibited by actinomycin D. Induction by insulin, but not by cyclic AMP, was enhanced by a higher concentration of amino acids. These results can be explained by supposing that in non-growing cells there is stable RNA which is involved in ODC induction, possibly mRNA of ODC, and that the observed induction is caused by inhibition of enzyme degradation and accelerated translation, while in growing cells this RNA is unstable and ODC induction is controlled at the level of transcription.
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PMID:Induction of ornithine decarboxylase in cultured mouse L cells. II. Effects of additions of amino acids and serum. 19 44

A single application of 17 nmol of 12-O-tetradecanoyl phorbol-13-acetate (TPA) to mouse skin caused a marked (200- to 400-fold) induction of ornithine decarboxylase (EC 4.1.1.17, L-ornithine carboxy-lyase) activity in mouse epidermal and epidermal-dermal preparations. No change in the basal level of 3':5'-cyclic AMP occurred in epidermal-dermal preparations within 30 min of TPA application. Intraperitoneal injection of the beta-agonist isoproterenol resulted in a dose-dependent accumulation of 3':5'-cyclic AMP occurred in epidermal-dermal preparations within 30 min of TPA application. Intraperitoneal injection of the beta-agonist isoproterenol resulted in a dose-dependent accumulation of 3':5'-cyclic AMP 10 min after injection, but caused no induction of ornithine decarboxylase. When isoproterenol was injected 10 min prior to an application of either 1.7 or 17 nmol of TPA, the magnitude of the ornithine decarboxylase induction was the same as induction with TPA alone. Topical application of 17 nmol of TPA caused no increase in the level of 3':5'-cyclic GMP present in the mouse epidermal-dermal preparations 2-20 min after application. Intraperitoneal injection of 1.75 mumol of dibutyryl 3':5'-cyclic GMP and/or butyryl derivatives of cyclic GMP caused a 6-fold increase in the level of cyclic GMP and/or butyryl derivatives of cyclic GMP in epidermal-dermal preparations within 5 min of injection, and the level remained elevated for at least 20-30 min. This dose of dibutyryl 3':5'-cyclic GMP was incapable of inducing ornithine decarboxylase. Injection of dibutyryl 3':5'-cyclic GMP 5 min before application of 1.7 nmol of TPA or 30 min before application of 17 nmol of TPA did not alter the magnitude of the ornithine decarboxylase induction produced by TPA alone. These results suggest that early increases in the total intracellular levels of either 3':5'-cyclic AMP or 3':5'-cyclic GMP are not part of the mechanism by which TPA induces ornithine decarboxylase in the epidermis.
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PMID:Dissociation of increases in levels of 3':5'-cyclic AMP and 3':5'-cyclic GMP from induction of ornithine decarboxylase by the tumor promoter 12-O-tetradecanoyl phorbol-13-acetate in mouse epidermis in vivo. 19 21

Pregnant mare serum gonadotrophin given intravenously to immature rats caused a maximal (x 70) increase in ornithine decarboxylase activity (ODC) at 3 h; enzyme activity declined to about ten times the control levels by 9 h and a second rise began after about 20 h. Anti-PMSG given 30 min after PMSG reduced the peak response by 70%. Actinomycin D, or cycloheximide, completely prevented an increase in ODC when given with PMSG, but only cycloheximide lowered the enzyme activity when given 18 h later. Ovine FSH plus LH also produced a peak in ODC at 3 h but the activity decreased quickly and by 9 h it was at the control level. Secretion of endogenous FSH and LH, induced by hourly injections of LH releasing hormone (LH-RH) increased ODC to the same extent as did the exogenous hormones; ODC was still higher than in the controls 4 h after the last dose of LH-RH. Increased endogenous levels of FSH and LH did not consistently raise ovarian cyclic AMP content and the increases found were much less than those obtained after injection of PMSG or FSH+LH. The results indicate that increased ODC is induced and maintained by the continual presence of gonadotrophin. The dependence of increased ODC upon increased cyclic AMP cannot be unequivocally determined because of important differences in the timing of the responses and the difficulty in determining biologically significant changes in cyclic AMP.
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PMID:Temporal changes in ovarian ornithine decarboxylase and cyclic AMP in immature rats stimulated by exogenous or endogenous gonadotrophins. 19 94

Heavy metal treatment (2 X 1 mg/kg per day) for 3, 5, and 7 days resulted in progressive augmentation in the incorporation of [14C]thymidine into hepatic DNA. In contrast with the observed enhancement in DNA synthesis, cadmium exposure tended to produce a decrease in the activity of hepatic ornithine decarboxylase (EC 4.1.1.17) at 1, 3, or 5 days with the lowest (34% of control values) enzymic activity seen after 7 days. A similar reduction in the activity of S-adenosylmethionine decarboxylase (EC 4.1.1.50) was observed in livers of rats treated with cadmium for 1-7 days. Subacute exposure to cadmium significantly lowered the hepatic levels of spermidine and spermine whereas the endogenous concentrated of putrescine remained unaltered. In addition to the observed effects on the biosynthesis of polyamines and DNA, heavy metal treatment produced stimulation of the hepatic adenylate cyclase (EC 4.6.1.1)--cyclic AMP system. Significant increases in the activity of hepatic adenylate cyclase and endogenous cyclic AMP levels were detected as early as 1 day and the observed alterations persisted during the entire 1-week period of cadmium exposure. The depression in polyamine formation was accompanied by enhanced DNA biosynthesis as well as stimulation in the adenylate cyclase-cyclic AMP system of rat liver.
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PMID:Sequential changes in hepatic polyamine, deoxyribonucleic acid, and cyclic adenosine 3',5'-monophosphate metabolism after subacute exposure to cadmium in rats. 19 91


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